WebClient vs RestClient: Which Should I Use for Synchronous Calls in Spring Boot?

Mar 11, 2026

I needed to make synchronous HTTP calls in a Spring Boot application, and I kept seeing conflicting advice. Some sources said to use WebClient. Others mentioned RestClient. The Spring documentation itself had changed over time.

Here’s what I found and why RestClient is the right choice for synchronous calls.

The Confusion

When Spring 5.0 came out in 2017, the documentation stated that WebClient would replace RestTemplate. This led to years of blog posts, Stack Overflow answers, and even AI recommendations suggesting WebClient for all HTTP calls.

The problem? WebClient is a reactive client. Using it for synchronous calls requires calling .block() to force blocking behavior on a non-blocking client.

@Service
public class UserService {

    private final WebClient webClient;

    public UserService(WebClient.Builder webClientBuilder) {
        this.webClient = webClientBuilder
            .baseUrl("https://api.example.com")
            .build();
    }

    public User getUser(Long id) {
        return webClient.get()
            .uri("/users/{id}", id)
            .retrieve()
            .bodyToMono(User.class)
            .block(); // Forces synchronous behavior
    }
}

This works, but it’s wrong for several reasons:

Unnecessary dependencies - You need to add spring-boot-starter-webflux even though you’re not using reactive features
Reactive overhead - WebClient creates reactive infrastructure (schedulers, buffers, operators) that never gets used
Complexity - You’re wrapping your head around Mono/Flux types when you just need a simple HTTP call

The Right Tool: RestClient

Spring 6.1 (released in 2023, included in Spring Boot 3.2) introduced RestClient specifically for synchronous HTTP calls. It has a modern, fluent API similar to WebClient, but it’s designed for the traditional thread-per-request model.

@Service
public class UserService {

    private final RestClient restClient;

    public UserService(RestClient.Builder restClientBuilder) {
        this.restClient = restClientBuilder
            .baseUrl("https://api.example.com")
            .build();
    }

    public User getUser(Long id) {
        return restClient.get()
            .uri("/users/{id}", id)
            .retrieve()
            .body(User.class); // Direct return, no blocking
    }
}

Same functionality, cleaner code, no reactive baggage.

Comparison

Aspect	RestClient	WebClient with .block()
Introduced	Spring 6.1 (2023)	Spring 5.0 (2017)
Purpose	Synchronous HTTP	Reactive HTTP
Dependencies	spring-web only	Requires spring-webflux
Return type	Direct objects	Mono/Flux wrapper
API style	Fluent	Fluent
Thread model	Thread-per-request	Non-blocking event loop
Virtual threads	Works naturally	Not designed for it
Learning curve	Simple	Steep (reactive concepts)

When to Use Each

Use RestClient when:

Building traditional Spring MVC applications
Making synchronous HTTP calls
You don’t need backpressure or streaming
Using Java 21+ virtual threads for concurrency

Use WebClient when:

Building Spring WebFlux reactive applications
Need non-blocking I/O with backpressure
Streaming large amounts of data
Your application is already on the reactive stack

@Service
public class ReactiveUserService {

    private final WebClient webClient;

    public ReactiveUserService(WebClient.Builder webClientBuilder) {
        this.webClient = webClientBuilder
            .baseUrl("https://api.example.com")
            .build();
    }

    // Correct use case: reactive streaming
    public Flux&lt;User&gt; getAllUsers() {
        return webClient.get()
            .uri("/users")
            .retrieve()
            .bodyToFlux(User.class);
    }
}

What About RestTemplate?

RestTemplate is in maintenance mode since Spring 5.0. It will be officially deprecated in Spring 7.1 (Spring Boot 4.2) and removed in Spring 8 (Spring Boot 5).

If you have existing code using RestTemplate, it still works. For new code, use RestClient.

// Old approach - still works but will be deprecated
Person person = restTemplate.getForObject("/persons/{id}", Person.class, id);

// New approach with RestClient
Person person = restClient.get()
    .uri("/persons/{id}", id)
    .retrieve()
    .body(Person.class);

RestClient Configuration

Spring Boot auto-configures RestClient.Builder as a bean. You can customize it in a configuration class.

@Configuration
public class RestClientConfig {

    @Bean
    public RestClient restClient(RestClient.Builder builder) {
        return builder
            .baseUrl("https://api.example.com")
            .defaultHeader("Authorization", "Bearer " + apiKey)
            .requestInterceptor(new LoggingInterceptor())
            .build();
    }
}

Error Handling

RestClient throws RestClientException for HTTP errors. You can customize error handling with onStatus.

public User getUser(Long id) {
    return restClient.get()
        .uri("/users/{id}", id)
        .retrieve()
        .onStatus(status -> status.is4xxClientError(),
            (request, response) -> {
                throw new UserNotFoundException("User not found: " + id);
            })
        .body(User.class);
}

Why the Spring Team Changed Course

The Spring documentation initially said WebClient would replace RestTemplate. This was later changed to “maintenance mode” status. Then RestClient was introduced.

A Reddit commenter put it well: “The introduction of RestClient is Spring putting up the white flag and saying ‘oh actually, the future is not reactive’.”

The virtual threads feature in Java 21 changed the calculus. Before virtual threads, reactive programming was one of the few ways to handle high concurrency with limited threads. Now, you can write simple synchronous code and let virtual threads handle the concurrency.

Bottom Line

For synchronous HTTP calls in Spring Boot, use RestClient. It’s the modern API designed for your use case. WebClient is great for reactive applications, but using .block() to force synchronous behavior adds complexity you don’t need.

Final Words + More Resources

My intention with this article was to help others share my knowledge and experience. If you want to contact me, you can contact by email: Email me

Here are also the most important links from this article along with some further resources that will help you in this scope:

👨‍💻 Spring Framework REST Clients Documentation
👨‍💻 Spring Boot REST Client Guide
👨‍💻 Reddit Discussion: WebClient for Synchronous calls

Oh, and if you found these resources useful, don’t forget to support me by starring the repo on GitHub!